Roof insulation adhesive

ABSTRACT

Excellent adhesives are prepared with: asphalt, about 40 parts by weight; an unsaturated rubber such as devulcanized tire rubber, 1 to 18 percent; a saturated rubber such as butyl rubber, 0.7 to 3 percent; a water-immiscible asphalt solvent, 20 to 41 parts; and water 5 to 20 parts. The devulcanized rubber, when used, may have been rendered more compatible with asphalt by having been previously compounded with about half its weight of polyethylene.

United States Patent Tarbell et a1.

[54] ROOF INSULATION ADHESIVE [72] lnventors: Harlan E. Tarbell,Torrance; Donald W. Mogg, Redondo Beach, both of Calif.; Frederick L.Shea, Johnson City, Tenn.

[73] Assignee: Grefco,1nc., Philadelphia, Pa.

[22] Filed: Oct. 14, 1968 [21] Appl. No.: 767,478

Related [1.8. Application Data [63] Continuation-in-part of Ser. No.493,218, Oct. 5,

1965, abandoned.

[52] US. Cl. ..260/4 R, 260/2.3, 260/5, 260/28.5 AS, 260/29.7 UA,260/33.6 UA, 260/33.8

UA, 260/41 R, 260/4l.5 R, 260/888, 260/889,

[51] Int. Cl ..C08d 9/12, C08f45/52 [58] Field of Search ..260/28.5 AS,4, 29.7 D, 29.7 UA

[561 References Cited UNITED STATES PATENTS 2,918,940 12/1959 Carr..260/28.5

[ 5] Feb. 22, 1972 Primary ExaminerJohn C. Bleutge AnarneyEverett H.Murray, Jr. and Francis D. Neruda [57] ABSTRACT Excellent adhesives areprepared with: asphalt, about 40 parts by weight; an unsaturated rubbersuch as devulcanized tire rubber, l to 18 percent; a saturated rubbersuch as butyl rubber, 0.7 to 3 percent; a water-immiscible asphaltsolvent, 20 to 41 parts; and water 5 to 20 parts. The devulcanizedrubber, when used, may have been rendered more compatible "with asphaltby having been previously compounded with about half its weight ofpolyethylene.

8 Claims, No Drawings ROOF INSULATION ADHESIVE The application is acontinuation-in-part of Ser. No. 493,218, filed Oct. 5, 1965, nowabandoned.

Although the use of bitumens such as asphalt and pitches in adhesiveformulations for roofing purposes is well known in the art, it isattended by serious problems and inconveniences.

First, there is the matter of application. When asphalt is used as theadhesive for securing insulation board and vapor barrier to the deck ofa roof, it is conventionally applied by a hot mop process. The solidasphalt is first melted and spread over the surface of the deck with amop. The vapor barrier, when used, is laid on the deck and covered withmolten asphalt. The board is then laid on the deck. Such an applicationprocess entails the use of heavy melting equipment and requiresrelatively long periods of time for melting the asphalt. In contrast, acold application adhesive can be applied immediately and thus makepossible high-production rates with the use of a minimum of equipment.Furthermore, another defect of the hot mop process is that it results inthe net deposition of quantities of asphalt far in excess of what isneeded for adhesion of the board to the roof. Any application processwhich would eliminate this excess of combustible hot mopped bitumenbetween the metal roof deck and roof insulation, would ultimately be ofsome benefit against the propagation of fire within a building andachieve significant reduction of the quantity of dense black smoke thatis generated by the burning of heavy concentrations of bitumen.

While the art of cold application adhesives is not new, its penetrationin the field of roof deck insulation has so far been primarily limitedto adhesives based on rubber dissolved in organic solvents, theso-called rubber cements. These rubber cements are rather difficult toproduce in that they require the use of heavy mixers and long mixingperiods; they are fairly expensive and in some cases they appear to gelon aging.

An object of this invention therefore is to provide bitumenbaseadhesives that can be applied at ordinary ambient temperatures. Anotherobject is to provide cold application adhesives that can be spreadeasily and economically and thus avoid the undesirable excess bitumendeposits that are usually laid down by the hot mop process. A furtherobject is to provide an easily prepared cold application adhesive forroof decks that is stable on aging before and after application.

These and other objects which will become apparent in the course of thedescription of this invention, have been accomplished by compoundingbitumens with both saturated and unsaturated rubbers in certain criticalproportions. The resulting compositions are diluted for workability withone or more organic solvents and contain a prescribed amount of water aswell as an emulsifying agent and a water-swelling clay.

The following examples will illustrate the new formulations and theirexcellent properties. They must not be construed however as limitationsof the invention beyond the scope of the appended claims.

EXAMPLE 1 Parts by weight Asphalt. softening point 145 F. 45 Unsaturated Rubber 5 VM&P naphtha, b.p. 248-284 F. 17 Trichloroethylenc12 Butyl rubber solution 5 Wyoming bentonite 1.5 Water 14.5

The unsaturated rubber used in this formulation was an asphalt-solublefinely divided reclaimed rubber prepared according to Example II of U.S.Pat. No. 3,338,849. It had a specific gravity of about 1.15, a bulkdensity of approximately 15 pounds per cubic foot and its particle sizewas such that 80 percent of it passed through a mesh screen and 100percent through a IO-mesh screen. The material consisted substantiallyof 40 parts by weight devulcanized rubber prepared from fiber-free wholetire scrap by the process of U.S. Pat. No. 3,051,990, 26 parts groundscrap polyethylene, 16 parts gilsonite, l 1 parts anthracite coal dustand 7 parts whiting. The

butyl rubber solution was a mineral spirit solution containing 30percent by weight of a butyl rubber made from a monomer mixtureconsisting of 98 percent isobutene and 2 percent butadiene. Loxite 8011,a product of the Firestone Tire and Rubber Company, is an excellentexample of this type of material. The bentonite used is marketed by theAmerican Colloid Company under the designation of Volclay 200.

The unsaturated rubber was dissolved in the asphalt by stirring for onehour at 400 F. The butyl rubber solution, the naphtha and thetrichloroethylene were added to the asphalt while stirring. A suspensionof the Wyoming bentonite in the water was then emulsified into theasphalt-rubber-solvent mixture.

On testing, the resulting adhesive composition was found to possessexcellent useful properties. The product is self-extinguishing in thatit will not support combustion in a can at 75 F. after ignition of itsvapors with a match. It does not run when applied to a piece of sheetmetal and burned to a char with a gas burner. It flows at 0 C. whenpoured from the can. It has good initial tensile tack when spread on apiece of metal and covered with insulation board. It does not completelysoak into an insulation board and yet wets it sufficiently for goodadhesion. It develops a tensile strength bond of over p.s.i. whensecuring two pieces of steel together. Its tendency to form a skin onits surface by solvent evaporation is relatively minor in that thecomposition after being poured and left standing for two hours at 75 F.retains sufficient adhesive power to secure insulation board to roofdeck. Finally, the adhesive composition is stable in storage, showing nonoticeable deterioration after 18 months.

EXAMPLE 2 Parts by weight Coal tar pitch, softening point 65 C. 30

Reclaimed tire rubber 6 Neoprene 6 Polyisobutylene 4 Carbontetrachloride 8 Methylene chloride 27 Water 17 Wyoming bentonite 2 Thepolyisobutylene was used was Enjay Chemical Companys Vistanex LM-MH.grade, a viscous, tacky semisolid containing less than 3 weight-percentvolatile matter and having a specific gravity of 0.92 and a StaudingerViscosity average molecular weight of 8,700 to 11,700. The reclaimedtire rubber used was a conventional preparation containing naturalrubber and SBR rubber, obtained from truck and automobile tires bydevulcanization according to the process of U.S. Pat. No. 3,051,990, asdescribed in Example I of U.S. Pat. No. 3,338,849.

To prepare the adhesive, the hot coal tar pitch was blended with theunsaturated rubbers by means of a high shear mixer. The polyisobutyleneand the solvents were added with stirring at reflux temperature and anaqueous suspension of the bentonite was emulsified into the resultingsolution.

The adhesive was found to be incombustible when stored in a can. Itproduced satisfactory bond between insulation board and metal.

Useful adhesive compositions within the scope of this inventioncomprise, on a weight basis: a bituminous substance having a softeningpoint within the range of to 250 F., 20 to 60 parts; a highlyunsaturated rubber, l to 30 parts; a saturated rubber, 0.5 to 12 parts;organic solvent, 10 to 50 parts; and water, 5 to 45 parts. Otheringredients such as hydrophilic clays or emulsifying agents are presentin small quantities.

These components may be added as undiluted liquids or solids, as thecase may be, or, if desired or appropriate, the formulation may be builtup from ingredients that are already partly compounded, dissolved oremulsified. In any event, the procedure to be followed is not toocritical provided that it substantially parallels those of the examplesand yields a fairly homogenous composition, and provided further thatthe exigencies of the formulation are respected in terms of proportionsand materials.

Among the bitumens that can be used in the present compositions are suchmaterials as asphalt, gilsonite, petroleum pitch, coal tar pitch, woodtar pitch, lignite tar pitch and so on, and mixtures thereof.

As to the rubber components, it has been seen and demonstrated thatthere must be present at least one nontacky highly unsaturated rubberand one tacky rubber. A highly unsaturated rubber, for the purpose ofthis invention, is one made principally from diene monomers such asbutadiene and isoprene, and which contains, on a molar basis, at least50 percent diene units. The function of this nontacky unsaturated rubberadditive is to prevent excess absorption of the liquid adhesivepreparation into insulation board or other porous materials and toincrease the cohesive strength of the applied adhesive and itsresistance to running on exposure to open flame. Materials that cansatisfactorily fulfill these functions in the presence of the othercomponents of our adhesive compositions include natural rubber,reclaimed devulcanized rubbers of various origins, synthetics such asstyrene-butadiene copolymers, neoprene and so on. Reclaimed rubbers arepreferred which have been devulcanized according to the process of U.S.Pat. No. 3,051,990. Said materials are especially preferred when theyare solubilized by compounding according to U.S. Pat. No. 3,338,849 intoformulations comprising 20 to 60 parts of the reclaimed rubber, 5 to 30parts of gilsonite and 12 to 50 parts of polyethylene.

The tacky rubber to be used in our compositions is generally one thatcontains less than percent unsaturated units on a molar basis, althoughthere are certain more highly unsaturated polymers of low molecularweight that are sufficiently tacky to be employed to some advantagehere. In any case, it is a rubber capable of providing an initialtensile strength of at least 0.5 psi to the bond provided by an asphaltadhesive preparation of the type disclosed herein, this when two steelplates bonded to each other with the adhesive are pulled apart in adirection perpendicular to their adhered surfaces. This componentprovides the initial tack to the freshly applied adhesive and yet doesnot interfere with the further functions of the composition. There canbe used for this purpose a variety of materials includingbutadiene-acrylonitrile copolymers and the so-called butyl rubbers,i.e., copolymers of isobutylene with isoprene or butadiene. These rubbermaterials, especially the unsaturated types, may contain variousconventional additives such as fillers, oils, accelerators and otherrubber chemicals as well as polymers, other than polyethylene.

The solid components just enumerated are blended or dissolved in one ormore organic solvents, preferably a hydrocarbon or a chlorinatedhydrocarbon. A list of useful solvents includes benzene, petroleumnaphtha, trichloroethylene, tetrachloroethane, pentachloroethane, carbontetrachloride, chloroform, toluene, xylene, kerosene and so on. Wheremore than one type of solvent is used, it has been found advantageous tomix hydrocarbon and chlorinated hydrocarbon solvents in proportions suchthat the specific gravity of the organic phase of the adhesivepreparation, bitumen and rubbers included, approximates l. Theflammability of the vapor generated by the liquid adhesive is also afactor that may be desirably considered.

As noted and illustrated earlier, water is used in formulating thepresent compositions. It may be slightly acidified and may containwetting agent to facilitate its dispersion throughout thebitumen-rubber-solvent system. Small amounts of hydrophilic colloidssuch as sodium montmorillonite or Wyoming bentonite are suspended in thewater before admixture with the organic phase. In this respect, 1 to 2percent by weight of such water-swelling clay will maximize thecontribution of the aqueous phase materials without unduly interferingwith the other properties of the adhesive compositions. Thiscontribution is evident both in the liquid adhesive preparation andafter application. First, there is a decrease in skinning of thepreparation on application as well as a decrease of vapor flammabilityduring application and drying. Also, the clay helps prevent running ofthe dry adhesive subjected to abnormal heat conditions.

An excellent all-purpose adhesive composition may be prepared, withinthe limits already described, by using, on a weight basis, 20 to 60parts of an asphalt melting between 1 30 and 190 F., 1 to 18 parts of anontacky unsaturated rubber containing, on a molar basis, more than 50percent of diene units, 0.7 to 3.0 parts of a tacky rubber containingless than 10 percent unsaturation, 20 to 41 parts of an organic liquidselected from the class consisting of hydrocarbons, chlorinatedhydrocarbons and mixtures thereof, and 5 to 20 parts water. For roofingpurposes, on the other hand, the most satisfactory results have beenobtained with compositions comprising, on a weight bases: from 43 to 47parts of an asphalt having a softening point within the range of to F lto 6 parts of a nontacky devulcanized rubber which preferablyconstitutes from 20 to 60 parts of an asphalt soluble preparationcomprising 5 to 30 parts gilsonite and 12 to 50 parts polyethylene; l to2 parts tacky saturated rubber; 25 to 37 parts of a mixture ofhydrocarbon liquids, the proportions of said components being such thatthe density of the asphaltrubber-organic liquid phase approximates 1gram per milliliter; and 10 to 16 parts water.

It will be evident to those skilled in the art that additives other thanthose considered part of this invention can be included in the presentformulations to accomplish special functions or to enhance thecontribution of the required components. Suffice it to say in thisrespect that there can be added such materials as fire retardants,fillers, rubber curing agents and so on.

What we have discovered in short is a readily prepared economicaladhesive composition which will not gel, separate or burn readily whilein storage, is easy to apply in that it spreads without difficulty andhas a very low tendency to skin over in open can or applicator, hasexcellent initial tack to hold roofing materials in place duringevaporation of the solvents and yet permits the sliding of suchmaterials into place, and finally possesses excellent aging propertiesin that bonds obtained from it increase in strength on aging.

What is claimed is:

1. An adhesive composition comprising a water-in-oil dispersion havingon a weight basis:

20 to 60 parts of a bitumen having a softening point within the range of1 10 to 250 F.;

1 to 30 parts of a nontacky unsaturated rubber containing at least 50diene units on a molar basis;

0.5 to 12 parts of a tacky saturated rubber containing less than 20%unsaturated units on a molar basis;

10 to 50 parts of a water-immiscible organic volatile solvent for thebitumen; and

5 to 45 parts water.

2. The composition of claim 1 wherein the bitumen is selected from thegroup consisting of asphalt, gilsonite, petroleum pitch, coal tar pitch,wood tar pitch, lignite tar pitch and mixtures thereof.

3. The composition of claim 1 wherein the unsaturated rubber isdevulcanized tire rubber.

4. A stable homogeneous adhesive composition comprising, a water-in-oildispersion having on a weight basis: 20 to 60 parts of an asphaltsoftening within the range of 130 to F.; l to 18 parts of a nontackyunsaturated rubber selected from the group consisting of natural rubber,reclaimed rubber, copolymers of styrene and butadiene, neoprene andmixtures thereof which contain, on a molar basis, more than 50 percentdiene units; about 0.7 to 3.0 parts of a tacky saturated rubber selectedfrom the group consisting of polyisobutylene, butyl rubbers, andmixtures thereof, containing, on a molar basis, less than 20 percentunsaturated units; 20 to 41 parts of an organic liquid solvent selectedfrom the class consisting of hydrocarbons, chlorinated hydrocarbons andmixtures thereof; and 5 to 20 parts water.

5. The composition of claim 4 wherein the organic liquid solvent isselected from the group consisting of benzene, petroleum naphtha,toluene, xylene, kerosene, trichloroethylene, tetrachloroethane,pentachloroethane, perchloroethylene, methyl chloride, carbontetrachloride, chloroform and mixtures thereof.

6. The composition of claim 4 wherein l to 2 percent of a water-swellingclay has been incorporated into the aqueous phase.

7. A roofing adhesive composition, comprising a water-inoil dispersionhaving on a weight basis: about 43 to 47 parts of an asphalt having asoftening point within the range of 140 to F., about I to 6 partsnontacky unsaturated devulcanized tire rubber; about 1 to 2 parts tackysaturated rubber selected from the group consisting of polyisobutylene,butyl rubbers and mixtures thereof; about 25 to 37 parts of a solventmixture of saturated hydrocarbon liquids and chlorinated hydrocarbonliquids in proportions such that the specific gravity of theasphalt-rubber-solvent mixture approximates l; and 10 to 16 percentwater.

8. The composition of claim 7 wherein the devulcanized tire rubberconstitutes 20 to 60 parts of a mixture also comprising 5 to 30 partsgilsonite and 12 to 50 parts polyethylene.

2. The composition of claim 1 wherein the bitumen is selected from thegroup consisting of asphalt, gilsonite, petroleum pitch, coal tar pitch,wood tar pitch, lignite tar pitch and mixtures thereof.
 3. Thecomposition of claim 1 wherein the unsaturated rubber is devulcanizedtire rubber.
 4. A stable homogeneous adhesive composition comprising, awater-in-oil dispersion having on a weight basis: 20 to 60 parts of anasphalt softening within the range of 130* to 190* F.; 1 to 18 parts ofa nontacky unsaturated rubber selected from the group consisting ofnatural rubber, reclaimed rubber, copolymers of styrene and butadiene,neoprene and mixtures thereof which contain, on a molar basis, more than50 percent diene units; about 0.7 to 3.0 parts of a tacky saturatedrubber selected from the group consisting of polyisobutylene, butylrubbers, and mixtures thereof, containing, on a molar basis, less than20 percent unsaturated units; 20 to 41 parts of an organic liquidsolvent selected from the class consisting of hydrocarbons, chlorinatedhydrocarbons and mixtures thereof; and 5 to 20 parts water.
 5. Thecomposition of claim 4 wherein the organic liquid solvent is selectedfrom the group consisting of benzene, petroleum naphtha, toluene,xylene, kerosene, trichloroethylene, tetrachloroethane,pentachloroethane, perchloroethylene, methyl chloride, carbontetrachloride, chloroform and mixtures thereof.
 6. The composition ofclaim 4 wherein 1 to 2 percent of a water-swelling clay has beenincorporated into the aqueous phase.
 7. A roofing adhesive composition,comprising a water-in-oil dispersion having on a weight basis: about 43to 47 parts of an asphalt having a softening point within the range of140* to 170* F., about 1 to 6 parts nontacky unsaturated devulcanizedtire rubber; about 1 to 2 parts tacky saturated rubber selected from thegroup consisting of polyisobutylene, butyl rubbers and mixtures thereof;about 25 to 37 parts of a solvent mixture of saturated hydrocarbonliquids and chlorinated hydrocarbon liquids in proportions such that thespecific gravity of the asphalt-rubber-solvent mixture approximates 1;and 10 to 16 percent water.
 8. The composition of claim 7 wherein thedevulcanized tire rubber constitutes 20 to 60 parts of a mixture alsocomprising 5 to 30 parts gilsonite and 12 to 50 parts polyethylene.